Atkins learnt that eating refined carbohydrates such as sugar and flour was the main cause of obesity in western society. When reducing the intake of high carbohydrate foods the body’s metabolism switches from using glucose as energy to burning stored fat. This is called ketosis and happens when insulin levels are low. Carbohydrates increase the glucose level (bloodsugar level). Therefore the body must produce more insulin the more carbs you eat and your body will not be able to use stored fat as fuel.

The Atkins diet restricts net carbs which is carbohydrates that can be digested. Net carbohydrates can be calculated by subtracting fiber from total carbohydrates.

The Atkins diet consists of four phases: induction, ongoing weight loss, pre-maintenance and maintenance.

Induction

The induction phase is the most restrictive phase of the Atkins Nutritional approach and it is recommended to stay in this phase for two weeks. The carb intake is limited to 20 net carbs pr day, which causes the body to enter ketosis.

Ongoing weight loss

During this phase the daily carbohydrate intake is increased by 5 net carbs pr week until you find your “Critical carbohydrate level” for losing weight and your weight is 4.5 kg (10 pounds) away from your target weight.

Pre-maintenance

The carbohydrate intake is increased by 10 net carbs pr week to find the maximum amount of carbohydrates you can eat before you start gaining weight.

Maintenance

In this phase you use what you’ve learnt in the previous phases to maintain your weight.